Insulating material.



I No Drawing.

CHICAGO, ILLINOIS, AND ROBERT J. SI-IOEMAKER, 0F

TOPEKA, KANSAS; SAID SHOEMAKER ASSIGNOR T0 SAID MACFARLAND.

' To all whom it may concern:

Be'it known that we, HELON B. MACFAR- LAND and ROBERT J. SHOEMAKER, citizens o the United States, residing at Chicago, in

= the county of Cook and State of Illinois, and

Topeka, in the county of Shawnee and State of Kansas, respectively, have invented certain new and useful Improvements in Insulating Material, of which the following is a specification.

Our invention relates to the production of a fibrous material suitable for use particularly as a heat insulator though probably susceptible of being used in other analogous situations.

The principal objects of the invention are, first, to provide an insulating material in the form of a relatively thin sheet or board adapted, for example,

to be placed in the walls of a building or other like structure,which will be tough and tenacious in its character so that it will not be readily torn, pliable in order that it may not be easily broken in handling or by vibration of the structure with which it is used, or other like causes, and at the same time sufliciently felt-like or cellular to make a good insulator, and which, furthermore, will be of such composition and texture that when it is rolled out or otherwise pressed or formed into sheets, these sheets will be of uniform thickness and density; and, second, to utilize,

for the production of such insluating sheets or boards, a raw material which is plentifully supplied by nature, and because not used to any extent in the arts has little or no commercial :value, and which, further- -more, can be converted into thedesired condition and form by methods that are simple, expeditious and inexpensive.

The invention contemplates using as a raw material certain sea plants, specifically theplant commonly called eel grass Zostera marina of the botanical family of N aimlacew.)

In this application we seek to patent our novel product as such. The novel features of the method whereby said product is produced is not claimed herein as the method is-the subject of a co-pending application filed by us of even date herewith bearing Serial No. 803,208.

The insulating material of our invention as follows, although it will be understood that the invention is not to be considered aslimited to the specifically Specification of Letters Patent;

Patented July 13, 1915.

Application filed November 26, 1913. Serial No. 803,207.

described process nor to the particular agents employed. The raw material, eel grass, is first cooked or boiled in an alkaline solutionpreferably a two per cent. solution of caustic sodafor a period of from one to six hours. The boiling may be. done either at atmospheric pressure or under steam pressure. This treatment frees and dlssolves out from the fibrous or cellular constituent of the plant, -a portion of the pectic, resinous and nitrogenous matters.

These last mentioned substances are removed by any suitable treatment, for example, by suspending the material in a large volume of water and agitating the same either mechanically or by means of compressed air. The fibrous constituent is then recovered from the water in any suitable manner. The product in this condition lacks the toughness,

desirable that a sheet of insulating material should have, particularly when employed in the situations above noted. In order to give the product these qualities, our invention contemplates further treatment as follows: A portion of the material subjected to the alkaline treatment above described is immersed in an acid bath. Any suitable acid may be used. Preferably we employ a very dilute sulfuric acid, the material being suspended in-this acid for'a short time, sa from five to fifteen minutes. x

Although the precise chemical reactions taking-place when the acid comes into contact with the material cannot be stated with absolute accuracy, due to the complex chemical character of the material, the acid apparently dissolves out the residue of the pectic, resinous and nitrogenous matter not removed by the alkaline treatment, frees the cellulose constituent from a large part of the.

(C6H10O5)11+(H2O)fl: 6 12 6) 1 After the acid treatment the material is again washed with water andsoluble substances. In physical structure the resultant material is a more or less gummy mass but still somewhat fibrous in character. If this material is rolled out into sheets it will be found to be somewhat more to remove the acidstability and closeness of texture which it'is following 7 brittle and more dense than is desirable, I

which has been treated only with the alkali.

For example, a very excellent product is obtained by mixing together, while both constituents are wet, seventy per cent. of the material treated with the alkali and thirty per cent. of the material treated first with thealkali and then with the acid. The mixing is advantageously carried on by sus- /pending both constituents inn large volume of water and agitating by compressed air, or mechanically, from one to six hours until the mixture is perfectly'homogeneous. The water is then drained off and the material rolled into sheets of the desired thickness.

The character of the product is such that these'sheets will be uniform in thickness, homogeneous in texture and of equal porosity throughout, besides being both very tough and very pliable. The material is not liable to decomposition by heat or water. A

heat insulating material to be effective and durable should have all of these qualities.

While a material composed as last described best exemplifies our invention, it is possible to obtain a useful product by mixing with raw eel grass the substance obtained from this plant by treating the same first with an alkali and then with an acid as described above. In other words, it is possible .to. substitute the raw material for the material boiled in the alkaline solution.

While we prefer to use for the production of our insulating compound the particular marine plant referred to, it is realized that our invention might be utilized for the pro- 0 duction of a product, which would have some if not all of theadvarrtageous features of the compound described,employ ing as a raw material other marine plants thanthe Zostera marina, or other vegetable matter. of a generally similar character.

One of the difficulties in utilizing marine plants for the production of boards or sheets suitable for insulating purposes is due to the difficulty of removing the mineral salts which such plants contain in excess because of the nature of their habitat. Our method successfully accomplishes this result, thereby making it possible to obtain a material which satisfies the several requirements of a conveniently handled and effective heat inducing the material; For example, in producing the preferred form of material it will be possible to omit the first washing. step,-

that is, the washing of the material after treatment with the alkali, since the removal of the non-fibrous, constituents freed by the boiling in the alkaline solution may be postponed until the washing which takes place when the acid treated material is suspended in water and mixed with the alkali treated ingredient. These obviously .may be varied as conditions'require. While the material of our invention, because of the characteristics described, is particularly useful as a heat insulating material for refrigerating plants, ice-houses, refrigerator cars, steel passenger cars, and the like, it will be obvious that it might be utilized to some advantage in "other situations where similar conditions are present. For instance, by suitably treating the sheets the material might be used for fireproofing purposes or for waterproofing. The material might also be advantageously used for deadening sound. 1

,We claim:

1. An insulating material consisting of fibers of Zostera; marina and hydrocellulose derived from the fibers of said plant mixed together'and in the form of a felted sheet of homogeneous texture.

2. An insulating material consisting of the fibers of Z ostem marina; and hydrocellu- -'lose derived from the fibers of said plant mixed together in the proportion of approximately seventy per cent. of the former to thirty per cent. of the latter and in the form of a felted sheet of homogeneous texture.

3. An insulating material consisting of a homogeneous mixture of the-fibers of the Zostera marina freed from non-fibrous constituents of the plant, and a gummy substance derived from the fibers of said plant.

4. An insulating material consisting of a homogeneous mixture of vegetable fibers] with a substance derived from vegetable fibers by hydrolysis.

5. An insulating material'consisting' of -.fibers of vegetable mattenfreed from nonfibrous material and hydro-cellulose derivedfrom like'fibers, mixed together and in the form of a felted sheet, homogeneous in texture and uniform in thickness.

6. .An insulating material consisting of fibers of Zostem marina freed from the nonfibrous constituents of theplant and a hydro-cellulose derived from like fibers, mixed 7 together and in the form of a felted sheet of homogeneous texture and substantially uniform thickness.

HELON B. MAGFARLAND. ROBERT J. SHOEMAKER.

Witnesses:

L. A; FALKENBERG, H. M. GILLnsrrE. 

